Bill Belichick can be seen often at Celtics games. He is usually smiling, and with good reason.

Belichick and his girlfriend Lynda Holliday were seen taking in Sunday night's Game 4 of the 2012 NBA Eastern Conference Finals, the Celtics taking on the Miami Heat at the TD Garden. Belichick is one of many Boston area sports celebrities that take in the Celtics on occasion (Jacoby Ellsbury was also at Game 4; David Ortiz loves to take in the Celtics during the Red Sox offseason). But when Belichick takes in a Celtics game, it's not to impress Lynda. It's to impress himself.

The Boston coaching fraternity has a lot of cross-interaction, and with good reason. Belichick was good friends with Terry Francona, the former Red Sox manager who is now employed by ESPN as a Sunday Night Baseball commentator. Claude Julien received a lot of well wishes during the Bruins' Stanley Cup run last year. Belichick has to love watching Doc Rivers coach the Celtics, who are now one win away from their third trip to the NBA Finals in the last five years. The Celtics put themselves in that position with a 94-90 win at American Airlines Arena in Miami on Tuesday night, giving the Celtics a 3-2 lead in the series with a home game for Game 6 on Thursday night to try and nail down the berth in the Finals.

When you look at the coaching matchup between Rivers and Miami head coach Eric Spoelstra, it is much like Belichick versus most any other NFL head coach: a huge mismatch in favor of the Bostons. You can look at both the Celtics and the Heat rosters from one to twelve, and you will find that Miami's 12 are perhaps better than Boston's on paper. But on the court, it is clear that the Celtics are the better team, and the reasons why, like the Patriots, always find their way back to the coach.

What the Celtics lack in youth and material, they make up for in maturity, grit and knowing how to close out games. It is painfully clear to all those Dolphin fans who also love basketball that Rivers is outcoaching the dickens out of Spoelstra. Despite the three-time NBA MVP and one of the best point guards in the business on the roster, the Celtics have out played the Heat most all the way, and if a few breaks had gone the way of the Celtics in Game 2, this series could be over right now.

Many observers agree that Miami lacks cohesiveness, unity, and a clear game plan on the offensive side of the ball. LeBron James and Dwyane Wade are being relied upon way too much to carry the play for the Heat, Spoelstra is not clear as to how to deal with the injured Chris Bosh, and other offensive weapons for the Heat like Mario Chalmers, Shane Battier or Mike Miller are either inconsistent or not trusted in the clutch. James has shown in past years to wilt under playoff pressure, save for perhaps that epic Game 7 with Cleveland against the Celtics in the 2008 East Semifinals.

Meanwhile, the Celtics have been able to withstand the loss of Avery Bradley, have been able to rely on guys like Mickael Pietrus, Keyon Dooling and Brandon Bass to give quality minutes when needed, and have watched Rajon Rondo meander into the same pantheon as Magic Johnson and John Stockton as an elite point guard (and Magic himself agrees with this postulation). Rivers has been masterful in switching defenses, rotating players at the right time, and making his players stick to their defense when needed.

Rivers has been, and unjustifiably so, one of the most underrated head coaches in the NBA. It is clear that he has elevated his coaching game to the highest levels in the league, and the fact that he has gotten five years out of the Big Three when three years were all that were originally expected is nothing short of remarkable. Paul Pierce, Kevin Garnett and Ray Allen, despite injuries and the effects of aging, still look both hungry and disciplined out there at all times; even the combustible Garnett, despite some episodes of flamboyance, looks terrific out there for someone of his energy and anger level.

Rivers has also helped the Celtics to focus on the game at hand, not two or three games down the road, something that Belichick also loves. The Celtics were able to withstand tough challenges from both Atlanta and Philadelphia in the early rounds and an 0-2 deficit here against Miami. The deflating 115-111 overtime loss in Game 2 would have destroyed the psyche of most teams, but the Celtics came back completely undaunted and won the next two games at home, and now captured a most delightfully unexpected Game 5 win at Miami to put them on the brink of the NBA Finals.

If the Celtics do manage to close out the Heat on Thursday night at the TD Garden, it will be interesting as to what happens to Miami. Spoelstra might be yanked as head coach, as he is still perceived as a coaching lightweight and doesn't seem capable of getting the most out of Miami's Big Three. Rivers, however, will add to his rich legacy as the head coach of a team which has had such coaches as Tom Heinsohn, Bill Fitch, K.C. Jones, and some guy named Red.

First of all, the Celtics have to hold serve at home one more time. The Garden will be rocking, and the Celtics will be in the Finals if they win at home. It looks to be one of the more memorable evenings at the TD Garden in its 17-year history. The building has had only two championships, not nearly as many as the old Boston Garden. But Thursday night should add to the growing legacy that the new Boston sports winter palace is collecting, little by little.

And maybe you'll see Belichick there also, watching his coaching colleague work his magic and admiring him for promoting the team concept like he does down in Foxborough. If the Celtics do continue on in the playoffs, a lot of the reason will be Rivers.